Well, they haven't intentionally been been doing that in the bullpen. They pay top dollar for late inning relievers only, they just haven't always worked out, But Strahm has been worth every penny. Alvarado would have been had he not been suspended. Seranthony still would have been had they kept him. Hoffman was cheap. Romano's the only bust and even he was a $10-12 million arm they got for less due his injury. Robertson was overpaid but prorated that was still the Alvarado money, at the end of the day.
As for the other guys, if you sign FAs for four-five years you're gonna get burned on a few of them But it is hardly a tragedy that they couldn't give out a few new ones while waiting to shed Casty and Walker, and there haven't actually been any position players worth extending (nor starting pitcher who'd take one).
Of course they still need to draft and sign and develop better, and the jury is certainly still out on Barber. Bohm and Stott weren't even his picks. And Ranger and Nola were both Amaro-era. But I think they've changed the blood several times. The black hole of the MacPhail years still loom.